U.S. patent number 5,434,552 [Application Number 08/185,043] was granted by the patent office on 1995-07-18 for trailer hitch security system with separate and selectively set loose connection and theft prevention alarms.
Invention is credited to Glenn L. Ems.
United States Patent |
5,434,552 |
Ems |
July 18, 1995 |
Trailer hitch security system with separate and selectively set
loose connection and theft prevention alarms
Abstract
A trailer hitch security system has a first audible alarm to
alert the driver of a towing vehicle of a loose connection with the
trailer, and of a loose connection between the ball of the trailer
hitch and the towing vehicle's frame. The system also has two
visual indicators alerting the driver of the state of the coupling
between the trailer and the vehicle. A second audible alarm is
automatically activated if the vehicle's ignition is turned off and
an unauthorized removal of the trailer is attempted. The second
audible alarm is loud and intermittent, thus alerting the driver of
unauthorized unhitching, or theft, of the trailer. The loud alarm
may be turned off only from within the cab of the vehicle, as
returning the trailer to the towing vehicle's ball will not
deactivate it. The second audible alarm is tied to a timer which
limits the sounding of the second audible alarm to a preset time
interval.
Inventors: |
Ems; Glenn L. (Rogers, AR) |
Family
ID: |
22679324 |
Appl.
No.: |
08/185,043 |
Filed: |
January 24, 1994 |
Current U.S.
Class: |
340/431; 280/432;
280/511; 340/687 |
Current CPC
Class: |
B60D
1/06 (20130101); B60D 1/065 (20130101); B60D
1/58 (20130101) |
Current International
Class: |
B60D
1/06 (20060101); B60D 1/58 (20060101); B60D
1/00 (20060101); G08B 021/00 () |
Field of
Search: |
;340/431,438,426,687,686
;280/432,477,507,511 ;200/61.44 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hofsass; Jeffrey A.
Attorney, Agent or Firm: Young & Thompson
Claims
What is claimed is:
1. A trailer hitch security system having a socket fixedly attached
to a trailer and a ball assembly fixedly attached to a towing
vehicle, said ball being adapted to be received by said trailer
socket so as to allow said trailer to pivot with respect to said
towing vehicle, comprising:
(a) first sensor means for detecting a loose coupling between said
trailer socket and said ball assembly;
(b) second sensor means for detecting a loose coupling between said
ball assembly and a frame of said towing vehicle on which said ball
assembly is mounted;
(c) first visual indicator means responsive to said first and
second sensor means, said first visual indicator means being
energized in response to a proper coupling of said trailer with
said towing vehicle and a proper coupling of said ball assembly
with said frame;
(d) second visual indicator means responsive to said first and
second sensor means, said second visual indicator means being
energized in response to a detected faulty coupling between either
said trailer and said towing vehicle or between said ball assembly
and said frame;
(e) first audible alarm means responsive to said first and second
sensor means, said first audible alarm means being energized in
response to a detected faulty coupling between either said trailer
and said towing vehicle or between said ball assembly and said
frame;
(f) second audible alarm means responsive to said first and second
sensor means, said second audible alarm means being energized in
response to an unauthorized uncoupling of said trailer from said
towing vehicle when said vehicle's ignition has been turned
off;
(g) means for causing said second audible alarm means to continue
to be activated in the event that said trailer is recoupled to said
vehicle after an unauthorized uncoupling; and
(h) switch means for deactivating said second audible alarm means
only from within said vehicle.
2. A trailer hitch security system according to claim 1 wherein
said ball assembly has a spherical part, a cylindrical bas,e and a
threaded shank part and comprises:
(a) a circular threaded opening axially aligned with said threaded
shank;
(b) a sensing plunger mounted for reciprocal movement within a
central bore formed vertically in said ball assembly, said sensing
plunger having a cylindrical portion integral with a circular
base;
(c) an "O" ring mounted within an annular cavity in said
cylindrical portion of said sensing plunger;
(d) a spring mounted in said central bore forcing said sensing
plunger to extend past an uppermost top surface of said ball;
(e) a spring retainer and switch mount providing support for said
spring and said sensing plunger and further housing said first
sensing means;
(f) a threaded retainer screwed onto said circular threaded opening
to seal said central bore from the elements in conjunction with
said "O" ring of said sensing plunger; and
(g) a chamber in the base of said ball for mounting said second
sensing means.
3. A trailer hitch security system according to claim 1, wherein
said first audible alarm means is a low volume buzzer located in a
cab portion of said towing vehicle to alert an operator of said
vehicle that the trailer hitch is faulty.
4. A trailer hitch security system according to claim 1, wherein
said second alarm system is the vehicle's horn.
5. A trailer hitch security system according to claim 1, wherein
said second audible alarm means is intermittently energized by a
flasher circuit.
6. A trailer hitch security system according to claim 1, wherein
said first and second sensor means are connected to a power supply
means via a two part connector plug between which an adaptor plug
may be inserted for connecting a second ball assembly to allow the
trailer hitch security system to operate with two trailers
connected thereto.
7. A trailer hitch security system according to claim 1, wherein
said first and second visual indicator means are a single dual
color light emitting diode.
8. A trailer hitch security system according to claim wherein both
of said first and second visual indicator means of said dual color
light emitting diode are energized in response to a first relay
controlled switch, said first relay being responsive to said first
and second sensor means.
9. A trailer hitch security system according to claim 1, wherein
said second audible alarm means is automatically set to be
energized whenever the vehicle's ignition is turned off and an
unauthorized uncoupling of the trailer hitch occurs.
10. A trailer hitch security system according to claim 1, further
comprising timing means adapted to interrupt power supplied to said
second audible alarm means after a preset period of time has
elapsed, thereby causing said second alarm means to become
deactivated.
11. A trailer hitch security system according to claim 10, wherein
said timing means and said second audible alarm means are energized
by closing a first relay controlled two pole, single throw switch,
thereby connecting said timing means and said second audible alarm
means to a power supply, each through an appropriate circuit
breaker.
12. A trailer hitch security system according to claim 11, wherein
said second relay controlling said two pole, single throw switch is
itself controlled by second relay controlled switch controlled to
switch upon the vehicle's ignition being turned off.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a security system for trailer
hitches, and in particular, to a novel trailer ball connected to a
security system having two separate alarms selectively set by the
driver, one alarm to signal a loose trailer connection, and the
other to alert the driver and those in the vicinity of unauthorized
unhitching, or theft, of the trailer.
Conventionally, trailer hitches are of the ball and socket type,
which allows a secure connection of a socket coupling member of the
trailer to the ball of the towing vehicle. The ball and socket
arrangement allows a tight connection of the trailer to the towing
vehicle, while allowing the trailer to pivot with respect to the
ball, thus permitting the vehicle and the trailer to negotiate
turns in the road.
However, vibrations, shock, wear and tear, accumulation of dirt, or
improper seating of the trailer ball over the socket may cause the
hitch assembly to become loose. This loosening may cause an
accidental uncoupling of the trailer socket from the ball of the
towing vehicle while the vehicle is in motion, with disastrous
results, both in personal injury and property loss. As the hitch
assembly is never visible to the driver while the vehicle is in
motion, a device to monitor the integrity of the trailer hitch
connection from within the cab of the vehicle is needed to assure
the safety the driver and to safeguard the trailer. Also needed is
a security device to monitor the trailer coupling for unauthorized
unhitching or theft of the trailer after the vehicle's ignition has
been turned off and to sound a loud alarm if such an unauthorized
uncoupling or theft is detected.
Various solutions have been proposed to indicate a secure trailer
hitch connection and to alert the driver of the towing vehicle of a
loose connection or of theft of the trailer. U.S. Pat. No.
2,564,520 to Biasdell discloses mounting a lamp on the trailed
vehicle which is energized when a proper connection is made. U.S.
Pat. No. 3,710,370 to Quilici et al. teaches mounting both visual
and audio indicators on an automobile's dash board, thus signaling
the improper coupling to the driver while the vehicle is in motion.
U.S. Pat. No. 4,593,264 to Engle discloses a circuit which actuates
a single warning signal (the vehicle's horn) when the ball-socket
coupling becomes loose and in the case of an attempted theft of the
trailer. Thus, in Engle '264, the vehicle's horn will sound during
normal connection and disconnection procedures, as well as when the
vehicle is in motion, should the trailer coupling become loose.
Sounding the vehicle's horn in the aforementioned circumstances is
undesirable, irritating and potentially dangerous. U.S. Pat. No.
4,627,633 to Gehman et al. also discloses a hitch uncouple
detecting and signaling apparatus, but does not, however, disclose
a trailer theft alarm means. A later patent to Engle, U.S. Pat. No.
5,159,312, provides for a double switch system wherein a signal is
provided upon detection of a loose connection of the ball to the
socket, as well as upon detection of a loose connection between the
ball and the towing vehicle frame structure. A warning is also
sounded upon unauthorized removal of the hitch. The alarm signals
are transmitted to a receiver, which may be in the cab of the
vehicle, or in a remote location.
All of the aforementioned systems use a single alarm, usually the
horn of the vehicle, to alert the vehicle's driver to a loose hitch
connection or an unauthorized removal of the trailer. Thus, the
horn may blast even when the vehicle is in motion, with
unpredictable effect upon the driver and surrounding vehicles.
Furthermore, none of the solutions proposed above teach any
selectivity in the setting of the alarms. The vehicle's operator is
therefore not able to selectively set only the loose connection
alarm, or only the theft detecting alarm.
OBJECTS OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
device having two alarms, one which is a low-key alarm to signal
the driver that the trailer connection is loose, and the other a
more blatant alarm, such as the existing theft alarm of the
vehicle, to signal an attempt at unauthorized removal of the
trailer.
It is another object of the present invention to provide visual
indicators which assure the driver that the trailer is secure, or
which alert the driver of an unsafe connection.
It is a further object of the present invention to provide a device
which engages automatically to monitor against theft of the trailer
upon switching the vehicle's ignition off.
It is a still further object of the invention to provide a theft
monitoring device which, upon unauthorized removal of the trailer
socket from the towing vehicle's ball, intermittently sounds a
blatant alarm which cannot be deactivated by merely recoupling the
trailer and the vehicle.
These and other objects of the invention will become apparent with
reference to the following drawings and specifications.
SUMMARY OF THE INVENTION
The foregoing and still further objects are achieved in a trailer
hitch security system that includes a single switch to activate the
system, a main sensor switch and a loose ball switch on the trailer
ball. The trailer alarm system further includes a Driving Mode
wherein a green light in the cab of the vehicle indicates that the
trailer is secure, and a red light and an intermittent audible
alarm, each activated by a separate relay, indicate unsafe coupling
conditions. The alarm system according to the invention also
includes a Park Mode, or alternatively, a Theft Monitoring Mode,
which is automatically activated when the ignition is turned off.
In the Theft Monitoring Mode, the vehicle's horn is intermittently
activated by the closing of a double-pole, single-throw switch also
tied to a timer if an unauthorized unhitching or theft of the
vehicle occurs. To deactivate the alarm, the operator must turn the
system off from within the cab of the vehicle, as merely returning
the trailer to the ball will not de-activate the sounding of the
horn. The timer will also shut the theft alarm off after a preset
period of time. A separate adaptor plug is provided to allow tandem
hauling of two trailers, both of which can be monitored by the
trailer hitch security system according to the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an exploded view of a trailer ball according to the
present invention; and
FIG. 2 is a detailed circuit diagram of the control circuit of the
trailer hitch security system according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 depicts an exploded view of the trailer ball assembly 1
according to the invention. The trailer ball 3 has a circular
threaded opening 5 axially aligned with the threaded shank 7 by
which the ball is secured to the towing vehicle (not shown). A
loose ball sensor microswitch 9 is mounted on the underside of the
ball assembly 1 and serves as a sensor to detect a loose connection
between the ball assembly 1 and the towing vehicle.
Within the central bore of the trailer ball is mounted, coaxially
with said threaded shank 7, a spring retainer and sensor switch
mount 11 which houses a trailer sensor microswitch 13 which acts as
a sensor to detect a loose coupling between the trailer ball 3 and
the towing vehicle's socket. Mounted in the spring retainer 11 for
reciprocal vertical movement in the central bore of the ball
assembly 1 is a spring 15 and a sensing plunger 17 having a
circular base and an integral cylindrical portion of a diameter
smaller than that of the circular base. The cylindrical portion of
the sensing plunger extends past the topmost surface of the trailer
ball 3 so that a coupling of the socket to the ball will depress
the plunger and activate the trailer sensor microswitch 13. Within
an annular cavity in the cylindrical portion of the sensing plunger
is an "O" ring 19 to seal, in conjunction with the threaded
retainer 21, the central bore within the trailer ball 1 from the
elements. The threaded retainer 21 is screwed in the circular
threaded opening 5 of the trailer ball 3. A loose coupling between
the trailer ball 1 of the vehicle and the socket (not shown) of the
trailer will cause the spring 15 to force the sensing plunger 17
axially away from the spring retainer 11, actuating the trailer
sensor microswitch 13. The trailer sensor microswitch 13 and the
loose ball microswitch 9 are connected by suitable wiring (29 in
FIG. 2) extending through the threaded shank 37 of the trailer ball
3 to a control circuit as described hereinbelow.
FIG. 2 shows a schematic of the circuit controlling the trailer
hitch security system according to the present invention. The
outline of the trailer ball 3 is depicted in phantom lines. Within
the trailer ball 3 are the trailer sensor microswitch 13 and the
ball sensor microswitch 9, connected by wiring 23. A two-part
mating plug connector 25 connects the wiring 23 to the remainder of
the control circuit. Optionally, for tandem hauling, an adaptor
plug 27 may be inserted between the two portions of the mating plug
connector 25. This allows for the connection a second trailer ball
assembly (not shown) to the control circuit, and thus to the
trailer hitch security system according to the present
invention.
The control circuit is generally comprised of two main parts: the
Auto Horn Module 29 and the Monitor Panel 31.
The Monitor Panel 31 draws its power from the vehicle's battery at
the battery terminals 33. One terminal of a 3-ampere circuit
breaker 35 is connected to the positive terminal of the battery 33,
and the other-terminal of the circuit breaker 35 is connected to a
power switch 37. The single contact of switch 37 is wired to one of
the two terminals of the plug connector 25, to send current through
the ball sensor microswitch 9, and through the trailer sensor
microswitch 13. The return path of the current is through the other
terminal of the plug connector 25, which is connected to power the
12-volt sensor relay 39.
Thus, as long as there is a secure coupling of the trailer's socket
onto the vehicle's ball, and a secure connection between the ball
and the vehicle's frame, microswitches 9 and 13 will be in their
closed positions, and sensor relay 39 will be powered. Switch 41,
controlled by sensor relay 39, has two contacts 43 and 45. If the
trailer is not secure, switch 41 is controlled to connect with
contact 43, and the red portion of a two color light emitting diode
(LED) 47 will be illuminated, signifying that one of the sensor
microswitches 9 or 13 is open. Additionally, if the trailer
connection is not secure, the 12-volt acc relay 49 controls switch
51 to connect to contact 53, thus providing power to the buzzer 55,
producing an audible alarm within the cab of the vehicle. The
12-volt acc relay 49 draws power from the accessory terminal 57 of
the vehicle through a 1-ampere fuse 59. If the trailer is secure,
switch 41 is controlled to connect with contact 45, which causes
the green portion of the two color LED 47 to illuminate. Thus, in
Driving Mode, if the trailer is secure, microswitches 9 and 13 will
be in their closed position, and the green LED will be illuminated,
because switch 41 will be controlled to connect to contact 45. If
the trailer is not secure, however, the red LED will be
illuminated, and switch 41 will be controlled to connect to contact
43, whereas switch 51 will be controlled to connect with contact
53, causing the buzzer to emit an audible alarm.
When the vehicle's ignition is turned off, the Park Mode is
automatically activated, and switch 51 is controlled to connect
with contact 61, which is wired to power a 10-ampere relay 63.
Relay 63 controls the two-pole, single-throw switch 65. Switch 65
has a first pole with contacts 67 and 69, and a second pole with
contacts 71 and 73. Contact 69 is wired to the vehicle's battery
through the 3-ampere circuit breaker 35 if the power switch 37 is
in its closed position. To enable the anti-theft alarm system, the
monitor panel should be left in its "ON" position in the Park
(anti-theft) Mode, by keeping switch 37 closed. Contact 61 of
switch 51 is also connected to one terminal of a timer 75, the
other terminal of the timer being wired to contact 67 of switch 65.
Timer 75 controls the length of time the vehicle's horn is to blast
should an unauthorized removal or theft of the trailer take place.
Contact 73 of switch 65 is connected to a flasher unit 77, which
causes the intermittent sounding of the vehicle's horn 79, or other
loud alarm. The remaining contact of switch 65, contact 71, is
wired to the vehicle's positive battery terminal through a
20-ampere circuit breaker 81.
Thus, in Park Mode, if the trailer is secure, switch 41 is
controlled to connect to contact 45, switch 51 to contact 61 (as
the acc relay is powered by the accessory terminal 57), and the two
pole, single throw switch 65 is in its open position. If an
unauthorized removal or theft of the trailer occurs, switch 65
closes because a current path to the switch has been established by
switch 41 switching from contact 45 to contact 43, which then
causes the vehicle's horn 79 to sound intermittently. The horn will
sound until either the monitor panel power switch 37 is turned to
its "OFF" (open position), which powers down the entire system, or
the time set on the timer 75 elapses. Returning the trailer to the
vehicle will not cancel the alarm. Preferably, switch 37 is located
in the cab portion of the vehicle, so that only the owner of the
vehicle may have access to it.
Modifications of the invention herein disclosed will occur to a
person skilled in the art and all such modifications are deemed to
be within the scope of the invention as defined by the appended
claims.
* * * * *